Test Bank for Building Java Programs 3/E
Stuart Reges, Marty Stepp
3rd Edition
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CSE 142, Summer 2009
Midterm
Exam, Monday, July 27, 2009
Name:
Section: ___________________ TA: ___________________
Student ID #:
You have 60 minutes to complete this exam. You may receive a deduction if you keep working after the instructor calls for papers. This exam is open-book/notes. You may not use any computing devices including calculators. Code will be graded on proper behavior/output and not on style, unless otherwise indicated. Do not abbreviate code, such as S.o.p for System.out.print, "ditto" marks or dot-dot-dot marks You do not need to write import statements in your code.
If you enter the room, you must turn in an exam before leaving the room. You must show your Student ID to a TA or instructor for your exam to be accepted.
Good luck!
1. Expressions (10 points)
For each expression in the left-hand column, indicate its value in the right-hand column. Be sure to list a constant of appropriate type and capitalization
e.g., 7 for an int, 7.0 for a double, "hello" for a String
Expression Value
3 + 3 * 8 – 2
109 % 100 / 2 + 3 * 3 / 2.0
1 - 3 / 6 * 2.0 + 14 / 5
1 + "x" + 11 / 10 + " is" + 10 / 2
10 % 8 * 10 % 8 * 10 % 8
2. Parameter Mystery (12 points)
At the bottom of the page, write the output produced by the following program, as it would appear on the console.
public class ParameterMystery { public static void main(String[] args) {
String soda = "coke";
String pop = "pepsi";
String coke = "pop";
String pepsi = "soda";
String say = pop;
carbonated(coke, soda, pop); carbonated(pop, pepsi, pepsi); carbonated("pop", pop, "koolaid"); carbonated(say, "say", pop); }
public static void carbonated(String coke, String soda, String pop) { System.out.println("say " + soda + " not " + pop + " or " + coke); } }
3. If/Else Simulation (12 points)
For each call below to the following method, write the output that is produced, as it would appear on the console:
public static void ifElseMystery(int a, int b) {
if (a * 2 < b) { a = a * 3;
} if (b < a) { b++; } else { a ; }
System.out.println(a + " " + b); }
Method Call Output
ifElseMystery(10, 2);
ifElseMystery(3, 8);
ifElseMystery(4, 4);
ifElseMystery(10, 30);
4. While Loop Simulation (12 points)
For each call below to the following method, write the output that is produced, as it would appear on the console:
public static void whileMystery(int x, int y) { int z = 0;
while (x < y && z < 4) { x = x * 2; y = y + 2; z++;
System.out.println(x + " " + y + " " + z);
Method Call
whileMystery(4, 3);
whileMystery(5, 7);
whileMystery(3, 18);
whileMystery(0, 4);
Output
5. Assertions (15 points)
For each of the five points labeled by comments, identify each of the assertions in the table below as either being always true, never true, or sometimes true / sometimes false.
public static int antCrawl(int max) { Random rand = new Random(); int height = 0; int falls = 0;
// Point A
while (height < max) { int r = rand.nextInt(4);
// Point B
if (r == 0 && height > 0) { height ; falls++;
// Point C
} else { height++;
// Point D
// Point E return falls;
Fill in each box below with one of ALWAYS, NEVER or SOMETIMES. (You may abbreviate them as A, N, or S.)
falls == 0 height > 0 height < max
Point A Point B Point C Point D Point E
6. Programming (15 points)
Write a static method closerDistance that takes two pairs of integers, x1 and y1 and x2 and y2, representing two ordered pairs (x1, y1) and (x2, y2) on an x-y plane. Your method should calculate each pair’s the distance from the origin (0, 0) and return the closer of the two distances as a real number. If the two points are the same distance from the origin, you may return either of the two distances, since they are equal.
For example, the point (12, 5) has a distance of 13.0 from the origin, and the point (9, 9) has a distance of 12.727922061357855 from the origin, so a call to closerDistance(12, 5, 9, 9) would return 12.727922061357855. Notice your method should not do any rounding.
Recall that formula to find the distance between a point (x, y) and the origin is given by the following formula:
7. Programming (15 points)
Write a static method named smallest2 that accepts a Scanner for console input as a parameter. The method repeatedly prompts the user for a sequence of integers until the user enters a negative number. The method then prints the smallest two nonnegative numbers entered by the user. (You may assume the user will enter at least 2 nonnegative numbers.) Notice you do not have to print the two smallest unique numbers entered by the user. For example, if the user enters 2, 2, and 3, the two smallest numbers entered are 2 and 2.
Here are some example calls to the method and their resulting console output (user input is bolded and underlined). Assume a Scanner named console was initialized earlier in the code before each method call.
Call smallest2(console); smallest2(console); smallest2(console); smallest2(console); Output number? 8
number? 10
number? 2
number? 1
number? 22
number? -1
smallest: 1
second smallest: 2
number? 5 number? 6 number? 7 number? 8 number? 9 number? -5
smallest: 5 second smallest: 6
number? 5
number? 5
number? 5
number? 5
number? -3
smallest: 5
second smallest: 5
number? 200 number? 100 number? -103
smallest: 100 second smallest: 200
Hint: If you are stumped, first write the code to keep track of and print out just the smallest number entered by the user. This code alone will get substantial partial credit.
8. Programming (9 points)
Write a method called printSquare that takes in two integer parameters, a min and a max, and prints the numbers in the range from min to max inclusive in a square pattern. The square pattern is easier to understand by example than by explanation, so take a look at the sample method calls and their resulting console output in the table below.
Call printSquare(1, 5); printSquare(3, 9); printSquare(0, 3); printSquare(5, 5);
Each line of the square consists of a circular sequence of increasing integers between min and max. Each line prints a different permutation of this sequence. The first line begins with min, the second line begins with min + 1, and so on. When the sequence in any line reaches max, it “wraps around” back to min
You may assume the caller of the method will pass a min and a max parameter such that min <= max.
For a maximum of 4 points, you may instead write a different method called printSquareLite that takes only one integer parameter representing the max number in the range and prints the numbers in the range from 0 to max inclusive in the same square pattern described above. The third column of output in the table above produces the same output as the call printSquareLite(3)
X. Extra Credit (+1 point)
Describe CSE 142 or your TA in two words or less.
(Any word(s) you write will get the +1 extra point.)